The present invention is related to apparatus adapted to transfer controlled volumes of particles from a storage pile and more particularly to drag chain conveyor assemblies whereby the material is removed from sides of the storage pile.
Many particulate materials such as ensilage, sawdust, vermiculite and others are stored in piles for later removal. Often, some type of control is necessary to enable delivery of the material at a constant volume. This is particularly important in the lumber industry where sawdust is often utilized as a fuel for lumber drying kilns. A continuous even volume of sawdust is necessary to operate a drier burner at optimum efficiency.
Ordinarily, particulate material is delivered to selected locations by conveyors. The method by which the particulate material is taken from a storage pile has, however, presented some problem. Sawdust in particular has a tendency to bridge over a conveyor inlet so as to block the inlet and thereby make volume control impossible.
U.S. Pat. No. 3,011,658 granted Dec. 5, 1961 discloses an apparatus by which the material may be effectively delivered from a storage pile to a delivery or discharge conveyor. By placing the storage pile at the center of a circular ring and dragging a number of interconnected scoops about the pile, an effective method of delivering material to a discharge conveyor is achieved. However, some difficulty has been noted in the particular configuration of the drag chain assemblies. Previously, such assemblies have been formed of loosely interconnected scoops or drag chain buckets. These buckets are pivoted at either longitudinal end to adjacent buckets. The connection points for the buckets are positioned between the individual buckets so that a gap is formed between adjacent buckets as the chain is moved about a circular path. Loose material will build up between these gaps and often will bind between adjacent buckets and thereby inhibit the flexibility of the entire chain. Flexibility of the chain is necessary in that the storage pile is ordinarily constantly changing in volume. The chains must flex in both an inward and outward direction so the bucket assembly may remain in contact with the pile sides. Ordinarily, material is delivered to the top of a pile. As the pile increases in size, the sides move outwardly and, as a result, force the drag bucket chain assemblies radially outward from the center of the stack. When material has been bound between the adjacent buckets, flexure of the chain is impaired and it (the chain) can no longer conform to the ever increasing stack radius. As the pulling ring continues to rotate the chains, the requirement for power to cause this rotation will increase and the efficiency of the delivery system will decrease.
It has therefore become desirable to obtain an improved form of drag bucket chain assemblies whereby no gap is created between adjacent individual drag buckets and therefore no binding of material between buckets may be possible.